聚氨酯复合改性沥青的制备与性能研究

为改善聚氨酯（PU）改性沥青的性能，实现其在道路工程领域的应用，将PU、岩沥青（RA）和基质沥青（BA）按照自定的室内工艺流程制备得到PU复合改性沥青，并探讨了制备工艺参数的适宜性。采用针入度、软化点、延度和旋转黏度试验优化了PU和RA的掺配方案，基于胶体理论分析了PU复合改性沥青的温度敏感性；利用动态剪切流变（DSR）和弯曲梁流变（BBR）试验研究了PU复合改性沥青的高、低温流变性能，应用多应力重复蠕变（MSCR）试验评价了PU复合改性沥青的抗永久变形能力，确定了PU复合改性沥青的PG分级温度；借助扫描电镜（SEM）试验观测了PU复合改性沥青的微观结构；通过红外光谱（FTIR）试验推断出PU与沥青发生的主要化学反应。结果表明：当RA添加量为5%时，随着PU添加量从1%增加到5%，PU复合改性沥青的针入度、软化点和延度分别提高了42%、4%和19%；当PU添加量为5%时，随着RA添加量从5%增加到15%，PU复合改性沥青的软化点增大了17%，但针入度和延度分别下降了64%和138%；添加3% PU、15% RA和5% PU、15% RA的复合改性沥青的PG高温等级均能达到82℃，添加5% PU、5% RA的复合改性沥青的PG低温等级为-22℃，说明添加PU改善了沥青的低温流变性能，而添加RA提升了沥青的高温流变性能；BA，PU和RA界面之间相容性良好，证明了所研究的制备工艺的合理性；在PU复合改性沥青内部存在异氰酸根和BA中芳香族化合物发生的加成反应，PU中的不饱和键与沥青中S—S键发生的交联反应，以及所形成的交联网状结构提高了PU复合改性沥青的抗低温变形能力。

Preparation and Performance Evaluation on Polyurethane Composite Modified Asphalt

The objective of this study was to improve the properties of polyurethane(PU)modified asphalt,which can be used in road engineering.The PU composite modified asphalt was prepared using PU,rock asphalt(RA),and base asphalt(BA)through a self-developed laboratory process,and subsequently,the suitability of the preparation process parameters was discussed.The composition of PU and RA was optimized by penetration,softening point,ductility,and rotational viscosity tests.The temperature sensitivity of the PU composite modified asphalt was analyzed based on the colloid theory.The rheological properties of the PU composite modified asphalt were investigated by dynamic shear rheology and bending beam rheology tests,also the multiple stress creep recovery test was performed to evaluate the permanent deformation resistance.Next,the Performance Grade temperature of the composite modified asphalt was determined.Scanning electron microscope was used to observe the internal microstructure of the PU composite modified asphalt.The key chemical reaction between PU and asphalt was explored by an infrared spectroscopy test.The results show that the penetration,softening point,and ductility of the PU composite modified asphalt improve by 42%,4%,and 19%,respectively,with an increase in the PU content from 1%to 5%,and when 5%RA was used.The softening point of the composite modified asphalt containing 5%PU improves by 17%with an increase in the RA content from 5%to 15%,whereas penetration and ductility decrease by 64%and 138%,respectively.The PG high temperature grade of both PU composite modified asphalt with 5%PU and 15%RA and 3%PU and 15%RA can reach 82℃.The PG temperature grade of PU composite modified asphalt with 5%PU and 5%RA was-22℃,indicating that the use of PU can improve the low temperature rheological properties,and the introduction of RA can increase the high temperature rheological properties with regard to BA.BA,PU,and RA perform a preferable compatibility,proving the feasibility of the proposed preparation method.Both obvious chemical reactions were exposed in the PU composite modified asphalt,namely,the addition reaction between the isocyanate and aromatic compounds in BA and the unsaturated bond in PU crosslinked with the S-S bond in BA.Additionally,the resistance to low temperature deformation is due to the crosslinked network structure that is formed.